Vehicle heater independent of the engine

ABSTRACT

The invention relates to a vehicle heater which is independent of the engine, has a burner head (9) and a flame tube (8) and is surrounded by a heat exchanger casing (10) through which a heat transfer medium can flow. The heat exchanger casing has connections (A; B) for inflow and outflow of the heat exchanger medium, and regulating sensors (20; 20&#39;; 22) arranged in the region of the connections are connected to a control device which regulates the operation of the vehicle heater in relation to the heat transfer medium temperature measured. The aim of the invention is also to have the alternative of the heat transfer medium being able to flow through the heat exchanger casing (10) in the opposite direction, the connections (A; B) for the inflow and the outflow of the heat transfer medium subsequently being interchanged, and the regulating values of the existing regulating sensors being adapted.

The present invention pertains to an engine-independent vehicle heater,with a burner head and a flame tube, which is surrounded by a heatexchanger jacket, through which a heat carrier medium flows, wherein theheat exchanger jacket has connections for an inlet and an outlet of theheat exchanger medium, and control sensors, which are connected to acontrol device that controls the operation of the vehicle heater as afunction of the heat carrier temperature measured, are arranged in thearea of the connections, and an overheating protection means may also beprovided.

A vehicle heater of the above-described type has been known from DE 4446 829 A1; even though the control device of this vehicle heater makespossible a defined, reliable operation of the heater corresponding tothe set points set, the inlet and the outlet of the heat exchangermedium are located at the heat exchanger jacket. Connection lineslocated there, leading from the vehicle engine, on the one hand, and tothe heat exchanger of the interior space of the vehicle, on the otherhand, inherently contain auxiliary means, such as a water pump andpossibly a bypass line and require a corresponding mounting space in thevehicle. The application and use of such a heater are consequentlylimited to a certain vehicle model. This is also true because of thefixed arrangement of the control sensors in the device, which makepossible only a single, defined operation for an individual vehicle. If,e.g., the design of the prior-art heater is to be simplified and theheat carrier temperature sensor is to be arranged on the outlet side atthe beat exchanger jacket, e.g., together with an overheating sensorarranged there, this leads to certain drawbacks in terms of a stable,uniform control operation of the vehicle heat exchanger in the directionof the interior space of the vehicle, because the heater is controlledin this case based on the heat carrier temperature detected at theoutlet-side end of the heat exchanger jacket, which is subject toshort-term variations, depending on whether the heat user to theinterior space of the vehicle is switched on or not (if no bypass lineis present).

Based on the known state of the art, the object of the present inventionis to provide a vehicle heater of the type described in theintroduction, which expands the possibilities of application and usewhile having a simple design and being reliable in operation.

The basic object of the present invention is accomplished by a heater ofthe type disclosed in claim 1.

The subject of the present invention is advantageously improved by thefeatures of claims 2 through 8.

Provisions are made according to the present invention for the heatcarrier medium also to be able to flow through the heat exchanger jacketin the reversed direction as desired, in which case the connections forthe inlet and the outlet of the heat carrier medium are transposed andthe control values of the existing control sensors are correspondinglyadapted.

The control sensors can now be connected mutually transposed to thecontrol device if the control device has plug-type connections, or theexisting control sensors may be mounted mutually transposed at the heatexchanger.

As an alternative, the control device may have for each control sensorat least one alternative control value for a reversed operation, whichcan be activated during reversed operation. The alternative controlvalue may be activated in this case by a signal, which is, e.g., anelectric signal, by means of a vehicle/heater interface, in which casethe signal coding may be assigned to a corresponding vehicle model (wirestrap, voltage signal) and is therefore independent from the heater.

In a preferred variant of the present invention, the alternative controlvalues are activated automatically by the control device (in aself-learning, self-adapting manner, own logic), especially by theevaluation of the temperature gradient between the control sensorsduring the operation of the burner.

Consequently, the heater may be used during operation as before. Forexample, a (first) control sensor, e.g., a temperature sensor, which ispositioned in the vicinity of the medium inlet into the heat exchanger(or at the medium outlet from the heat exchanger), may assume thesending of a signal for the on-off control of the heater. Anothercontrol sensor, e.g., an overheating temperature sensor, which ispositioned in the vicinity of the medium outlet from the heat exchanger,assumes the overheating protection function and the outflow temperaturelimiting function.

If the reversed operation with opposite direction of flow in theheater-heat exchanger is now to be set up, the connections for the inletand outlet of the heater in the heat carrier circuit are transposed, inwhich case the above-mentioned first control sensor (which is nowpositioned in the vicinity of the medium outlet from the heat exchanger)assumes the outflow limitation function, while the above-mentioned othercontrol sensor (which is now positioned in the vicinity of the mediuminlet into the heat exchanger) assumes the overheating protectionfunction and the signal sending function for the on-off control of theheater.

Consequently, mutual flow of the heat exchanger medium is permitted bythe present invention in the same heater. Changes and modifications onthe hardware of the device are not necessary, as a result of which noadditional design effort becomes necessary and the field of applicationof the device is markedly expanded as well. The possible applicationsare, in particular, doubled, while the number of given variants of thedevice remains the same. The advantages of performing the temperaturecontrol in the water inlet in the case of devices using water as themedium may be maintained and used with both directions of flow. Flow maybe selected in one direction or another in the vehicles, depending onthe boundary conditions at the time of planning and design. The articlenumber of the device may be maintained, which leads to advantages interms of logistics and disposition. The installation and the maintenanceof the heater can be simplified and optimized in terms of costs due tothe variable connection to the vehicle circuit.

The present invention will be explained in greater detail below on thebasis of two exemplary embodiments with reference to the attacheddrawings, in which:

FIG. 1 shows a schematic representation of a vehicle heater in a heatcarrier circuit with an upstream internal combustion engine and adownstream vehicle heat exchanger in an application according to thestate of the art, and

FIG. 2 shows the vehicle heater according to FIG. 1 in an applicationwith reversed direction of flow.

FIG. 1 shows a vehicle heater, whose principal features are known.

A flame is generated in a combustion chamber joining a burner head 9,for which purpose combustion air is fed to the burner head by acombustion air blower (not shown) and fuel is fed to it via a fuel pump(not shown). The fuel is burned in the burner head 9. The flamepropagates to the right in FIG. 1 in the area of a flame tube 8. Theflame tube is surrounded by a heat exchanger jacket 10, which is ametallic double-walled housing with an inner gas jacket and an outerwater jacket.

Water enters as the heat carrier medium a closed circuit, arriving fromthe engine 100 of a motor vehicle and flowing, being delivered by awater pump 5, through an inlet connection A into the heat exchanger.Between the inner gas jacket and the outer water jacket, the heater heatexchanger has helical turns, in which the water flowing through the heatexchanger is heated by the hot gases of the flame in the flame tube 8.

The heated water leaves the heat exchanger of the heater through theoutlet connection B and reaches from there the heat exchanger (HE) 50proper of the vehicle for heating the interior space of the vehicle. Thewater is again returned after the latter heat exchanger 50 into thecooling circuit of the internal combustion engine 100 in order to form aclosed circuit in the vehicle heater.

In addition, FIG. 1 shows a bypass line BL, whose purpose is to makepossible the circulation of the water through the heat exchanger jacket10 with the heat exchanger 50 closed.

An inlet-side heat carrier temperature sensor 20 in the form of a watertemperature sensor, whose output signal is sent to a control device, islocated in the vicinity of the inlet connection A.

Instead of the inlet-side heat carrier temperature sensor 20, it is alsopossible to provide an outlet-side heat carrier temperature sensor 20',as is known per se.

An overheating temperature sensor 22 is also located at the right-handend of the heat exchanger jacket 10 or of the flame tube 8. Thisoverheating temperature sensor 22 is designed as the water temperaturesensor 20 or 20' used for the control.

The overheating temperature sensor 22 also sends an output signal to thecontrol device. Both output signals, that from the sensor 20 or 20' andthat from the sensor 22, are subjected to an analog-digital conversionin the control device and are evaluated by a microprocessor according todefined criteria, as is known in the prior art. The burner is ultimatelydriven such that the preset upper and lower temperature levels aremaintained in the heat exchanger jacket 10, i.e., they are not overshotand undershot. The control sensor 20 or 20' consequently assumes thesending of the signal for the on-off control of the heater. The controlsensor 22 assumes the overheating protection and the outflow temperaturelimitation.

Without changing the hardware, the above-mentioned vehicle heater cannow be arranged in the closed heat carrier circuit according to FIG. 2such that the direction of flow in the heater jacket 10 is reversedcompared with the design variant according to FIG. 1. The connection Aof the heater heat exchanger now becomes the outlet connection, and theconnection B becomes the inlet connection. It is self-explanatory thatthis leads to different connection lines from and to the engine 100 andfrom and to the heat exchanger 50. The heat exchanger 50 and the waterpump 5 may consequently be arranged in another location in a motorvehicle. The installation and the maintenance of the vehicle heater canbe simplified and optimized with respect to costs due to the variableconnection A or B to the vehicle circuit. The design boundary conditionsin a vehicle can consequently be taken into account better.

As was stated, the hardware of the vehicle heater remains unchanged.This applies, above all, to the control sensors 20 or 20' and 22, whichare installed in the heat exchanger system, but are now connected to thecontrol device differently or are associated with other, alternativecontrol values with unchanged connection to the control device in orderto establish a satisfactory, predetermined heater and control operationof the vehicle heater. In particular, the control sensor 20 assumes theoutflow temperature limitation function, and the control sensor 22 or20' assumes the overheating protection function and the signal sendingfunction for the on-off control of the heater.

The alternative values stored in the control device can be activated bya signal (e.g., electric signal, by means of the vehicle-heaterinterface). The signal coding is associated with the correspondingvehicle (wire strap, voltage signal) and is therefore independent fromthe heater.

It should also be mentioned that independently patentable featurescontained in the subclaims shall have a corresponding independentprotection despite the formal reference to the principal claim. All theinventive features contained in all the application documents also fallwithin the scope of protection of the present invention.

We claim:
 1. An engine-independent vehicle heater, comprising:a burnerhead; a flame tube connected to said burner head; a heat exchangerjacket surrounding said flame tube; a heat carrier medium flowingthrough said jacket, said heat exchanger jacket having connections foran inlet and an outlet of said heat exchanger medium; control sensorsconnected to a control device for supplying information based on asensing operation; and control means for controlling the operation ofthe vehicle heater as a function of the heat carrier temperaturemeasured by said control sensors, said control sensors being arranged inthe area of said connections, said heat carrier medium flowing throughsaid heat exchanger jacket in either of two directions to provide aforward or a reversed direction as desired, said connections for theinlet and the outlet of the heat carrier medium being transposed in saidreversed direction said controller using one of a first control valueand a second control value for controlling said the operation of thevehicle heater as a function of the heat carrier temperature measured bysaid control sensors depending upon whether said heat carrier medium isflowing through said heat exchanger jacket in said forward or in saidreversed direction.
 2. The vehicle heater in accordance with claim 1,wherein said second control value, as an alternative control value canbe activated by a signal.
 3. The vehicle heater in accordance with claim2, wherein said control has a signal coding associated with acorresponding vehicle model.
 4. The vehicle heater in accordance withclaim 1, wherein said second control value, as an alternative controlvalue is automatically used by said control device.
 5. The vehicleheater in accordance with claim 4, wherein said sensor uses one of saidfirst control value or said second control value based on an evaluationof the temperature gradient between the control sensors during theoperation of the burner.
 6. An engine-independent vehicle heater,comprising:a burner head; a flame tube connected to said burner head; aheat exchanger jacket surrounding said flame tube, said jacket having afirst inlet/outlet connection and a second inlet/outlet connection; aheat carrier medium flowing through said jacket, said heat exchangerjacket inlet/outlet connections being provided for intake and outflow ofsaid heat exchanger medium; a first control sensor disposed in saidjacket adjacent to said first inlet/outlet connection; a second controlsensor disposed in said jacket adjacent to said second inlet/outletconnection; and control means for controlling the operation of thevehicle heater as a function of the heat carrier temperature measured bysaid control sensors, said control sensors being arranged in the area ofsaid connections, said heat carrier medium flowing through said heatexchanger jacket in either of two directions to provide a firstdirection of flow from said first inlet/outlet connection to said secondinlet/outlet connection and a second direction of flow from said secondinlet/outlet connection to said first inlet/outlet connection asdesired, said control means including switch over means for adaptingsaid control sensors depending upon a direction of flow, said switchover means including at least one control value associated with saidfirst direction and one control value associated with said seconddirection and said switch over means switches said control means betweenuse of said control value associated with said first direction and saidcontrol value associated with said second direction.
 7. The vehicleheater in accordance with claim 6, wherein said switch over means isactivated by an electrical signal.
 8. The vehicle heater in accordancewith claim 7, wherein said switch over means is activated by a signalcoding associated with a corresponding vehicle model.
 9. The vehicleheater in accordance with claim 8, wherein said switch over meansswitches over based on an evaluation of the temperature gradient betweenthe control sensors during the operation of the burner.
 10. The vehicleheater in accordance with claim 6, wherein said control means includesan overheating protection means.
 11. A method of using anengine-independent vehicle heater, comprising:providing a burner head;providing a flame tube connected to said burner head; providing a heatexchanger jacket surrounding said flame tube, said jacket having a firstinlet/outlet connection and a second inlet/outlet connection providingtwo different possible operational flow directions through said jacket;selecting one of said two different possible operational flowdirections; providing a heat carrier medium flowing through said jacket,said heat exchanger jacket inlet/outlet connections being provided forintake and outflow of said heat exchanger medium; providing a firstcontrol sensor disposed in said jacket adjacent to said firstinlet/outlet connection; providing a second control sensor disposed insaid jacket adjacent to said second inlet/outlet connection; andcontrolling the operation of the vehicle heater as a function of theheat carrier temperature measured by said control sensors, said controlsensors being arranged in the area of said connections, said heatcarrier medium flowing through said heat exchanger jacket in either oftwo directions to provide a direction of flow from either said firstinlet/outlet connection to said second inlet/outlet connection or fromsaid second inlet/outlet connection to said first inlet/outletconnection as desired, said control means adapting said control sensorsdepending upon a direction of flow.
 12. The method in accordance withclaim 11, wherein adapting said control sensors by said control meansincludes mutually transposing connections to said control sensors. 13.The vehicle heater in accordance with claim 11, wherein adapting saidcontrol sensors by said control means includes control sensors mountedat said heat exchanger mutually transposed.
 14. The vehicle heater inaccordance with claim 11, further comprising providing the controldevice for each said control sensor with at least two control values,one for each direction of operation, said control means activatingcontrol values depending upon said direction of flow.